A combine harvester is a machine that is used to harvest grain crops. The objective is to complete several processes, which traditionally were distinct, in one pass of the machine over a particular part of the field. Among the crops that may be harvested with a combine are wheat, oats, rye, barley, corn, soybeans, and flax or linseed. The waste (e.g., straw) left behind on the field includes the remaining stems and leaves of the crop having limited nutrients which may be, for example, chopped and spread on the field or baled for feed and bedding for livestock.
The cut crop may be picked up and fed into the threshing and separating mechanism of the combine, typically consisting of a rotating threshing drum to which grooved steel bars may be bolted. These bars thresh or separate the grains and chaff from the straw (sometimes referred to as residue) through the action of the drum against the concaves, i.e., shaped “half drum,” that may also be fitted with angled steel bars (e.g. rub bars) and a meshed grill, through which grain, chaff and smaller debris may fall, whereas the straw, being too big or long, is carried through to the outlet. Typically, the drum speed may be variably adjustable and the distance between the drum and concave may be finely adjustable laterally and together, to achieve optimum separation and output.
In an axial flow combine, this threshing and separating system serves a primary separation function. The harvested crop is threshed and separated as it is conveyed between a longitudinally arranged rotor and the inner surface of an associated chamber comprising threshing and separating concaves. The cut crop material spirals and is conveyed along a helical path along the inner surface of the chamber until substantially only larger residue remains. When the residue reaches the end threshing drum, it is expulsed out of the rear of the combine. Meanwhile, the grain, chaff, and other small debris falls through the grates in concaves onto a conveyor system. For ease of reference, this smaller particulate crop material that contains the grain and chaff is referred to as threshed crop. The threshed crop still needs to be further separated from the chaff by way of a winnowing process.
Clean grain is separated out of the threshed crop by way of a flat cleaning system that can include a chaffer and sieves. Generally, the cleaning system operates by blowing air through the threshed crop to winnow the chaff and then sieving the grain to separate the grain from other particulates. The chaffing and sieving system on most modern combines operates on the assumption that the conveyor system delivers a fairly uniform grain bed. For example, the chaffing process optimally works on an assumed range of thicknesses of separated crop in a grain bed, which allows fans to blow off the chaff. If the thickness of material in the grain bed is too thick, the airflow supplied will be insufficient. Furthermore, the sieves may be unable to process the grain quickly enough, such that if threshed crop is delivered too quickly to one portion of the sieve area in the grain bed, the system may dog or the yield of the grain in the area may be reduced.
Conventional operation procedures for combine operation recommend that an operator visually and manually inspect the grain bed to determine if the grain bed is uniformly distributed. Currently, this requires the operator to perform a kill stall, whereby the operator stops the combine, gets out of the cab, accesses the grain bed or conveyor system, and checks for uniform or uneven distribution. If the grain bed is uneven, the operator can adjust mechanisms in the separator system manually until the grain bed is substantially uniform. This process is labor intensive and requires a skilled operator. The prior art does not include a system with sensors to alert the operator of the uniformity of the grain bed without requiring manual/visual inspection by the operator, which generally requires the operator stop harvesting. Furthermore, because the prior art does not teach sensors for monitoring uniformity of the grain bed, no automated feedback systems are available to optimize the cleaning system while harvesting.